The drunken monkey hypothesis got some extra support at last week’s meeting for the American Association for the Advancement of Science (AAAS). The controversial theory published by scientists Robert Dudley and Dustin Stephens claims that the primate ancestors of early humans evolved the ability to digest alcohol because of their habit of eating fermented fruit that they found on the ground.

Erin Wayman of Science News reports that biochemist Steven Benner of the Foundation for Applied Molecular Evolution performed an unusual “re-enactment” to demonstrate how advanced primates’ ability to metabolize alcohol has changed over time. According to Benner, the ancestor of modern chimps, gorillas, and humans that appeared about 10 million years ago had 50 times the ability to metabolize alcohol seen in other monkey groups. That gene has been passed down to us.

He noted that gorillas, chimps, and humans all forage for food on the ground, which is often bruised or rotten and in various stages of fermentation. Arboreal monkeys roaming through the tree branches can presumably find plenty of fresh fruit — and, therefore, they never developed the special gene. Orangutans, while often considered quite close to humans in intelligence and creativity, also lack the gene.

Since the familiar monkeys that swing through the trees can’t actually tolerate alcohol very well, the “drunken monkey hypothesis” might be a bit of a misnomer. However, the “alcoholic ape theory” just doesn’t have that same swing.

By the way, was the 2013 meeting of the AAAS all apes, all the time? One might be forgiven for thinking so.

Researchers from the Netherlands presented findings that chimps suffering from anxiety and post-traumatic stress disorder can benefit from prescription anti-depressants. Tetsuro Matsuzawa from Kyoto University’s Primate Research Institute offered video evidence that the short-term memory of chimps is far superior to that of humans.

New evidence for the “drunken monkey hypothesis” is only one of several reports at the conference aimed at developing a greater understanding of our nearest relatives.